求救;怎麼向一個文件追加數據

Question

try 
{
BufferedWriter out = new BufferedWriter(new FileWriter("filename", true));
out.write("aString");
out.close();
}catch (IOException e) {}
在构造FileWriter对象时添加一个参数就可以了！
你试试看！

Answer 1

to luodi(无知者无畏)　:
  不知我的观点对不对？你的思路是怎样实现的！

Answer 2

BufferedWriter out = new BufferedWriter(new FileWriter("filename", true));
这个方法是可行的。 

Answer 3

可以用两个线程，一个线程负责读文件，一个线程负责写文件
两个线程互斥，我以前写过一段程序就是这样做的，完全可以
对同一个文件进行输入输出处理！ 可否 share 代码？ 

Answer 4

/**************
  The Thread Test Example
**************/     
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;public class ThreadTest extends JFrame
{
     private boolean available = false;
     private static BufferedReader in = null;
     private static BufferedWriter out = null;
     private char str[] = new char[1];
     private int finish = 1;
     JButton    read = null,
                write = null;
     JTextArea  readArea = null,
                writeArea = null;
     JPanel     buttonPane = null,                  
                textPane =null;
     static WriteThread wt = null;
     static ReadThread rt = null;   
     boolean readstart = false , writestart = false ;         class readListener implements ActionListener
    {
     public void actionPerformed(ActionEvent e)
     {                  
     if(e.getActionCommand()=="read")
         {             
            readArea.setText("");available = true; readstart = true ;rt.start(); 
         }
     else
         {          
            writeArea.setText("");available = false ;writestart = true ;wt.start();
         }
     }
    }
    
     public ThreadTest()
     {
      super("线程测试示例");     
      Container pane = getContentPane();     
      pane.setLayout(new BorderLayout(0,6));
     
        buttonPane = new JPanel();
      read = new JButton("按下开始读文件");  
      read.setFont(new Font("宋体", Font.PLAIN, 20));
      read.setActionCommand("read");
      read.addActionListener(new readListener());
      write = new JButton("按下开始写文件");
      write.setFont(new Font("宋体", Font.PLAIN, 20));
      write.setActionCommand("write");
      write.addActionListener(new readListener());
      buttonPane.setLayout(new GridLayout(1,2,10,0));
      buttonPane.add(read);
      buttonPane.add(write);
      pane.add(buttonPane,BorderLayout.NORTH);
     
      textPane = new JPanel();
      readArea = new JTextArea(20,20);
      readArea.setEditable(true);
      readArea.setText("");
      readArea.setLineWrap(true);
      readArea.setWrapStyleWord(true);
      writeArea = new JTextArea(20,20);
      writeArea.setEditable(true);
      writeArea.setText("");
      writeArea.setLineWrap(true);   
      writeArea.setWrapStyleWord(true);
textPane.setLayout(new GridLayout(1,2,10,0));
      textPane.add(new JScrollPane(readArea));
      textPane.add(new JScrollPane(writeArea));
      pane.add(textPane,BorderLayout.SOUTH);
      setSize(400,200);
     }
     
     public synchronized int readOperation() 
     {     
        int flag = 0;         
        while (available == false ) 
        {
            try {
             read.setText("读线程堵塞");            
                wait();
            } catch (InterruptedException e) { }
        }
       try{
             if ( (in.read(str))!=(-1) )
                  {
                   read.setText("读线程开始");
                   readArea.append(new String(str));
                        if (finish == 1 && writestart == true)
                        {available = false;}
                        notifyAll();                        
                   }
             else 
                { 
                  flag = (-1);
                  available = false;
                  readstart = false ;
                  finish = 0;  
                  in.close();   
                  read.setText("读线程结束");           
                  notifyAll();
                }
           }catch(Exception e){System.out.println(" read error");}     
              
        return flag;
     }
     
     public synchronized void writeOperation(String st,int over) 
     {     
        if (over ==0)
          {
             try{out.flush();}catch(Exception e){}
             available = true;
             writestart = false ;
             finish = 0;            
            try{ out.close(); }catch(Exception e){}
             write.setText("写线程结束");
             notifyAll();
             return;
          }
        while (available == true )
         {
            try {
                write.setText("写线程阻塞");                
                wait();
                } catch (InterruptedException e) { }
        }
        try {
         write.setText("写线程开始");  
                out.flush();
         out.write(st);
             }catch(Exception e){System.out.println(" write error");}  
        writeArea.append(st);
        if (finish == 1 && readstart == true)        
             available = true;             
        notifyAll();
    }
     
     public static void main(String[] args)
     {
      ThreadTest tt = new ThreadTest();
try {
      in = new BufferedReader(new FileReader("a.txt"));
                out = new BufferedWriter (new FileWriter("a.txt",true));
           }catch(Exception e){ System.out.println(" initial error");}        wt = new WriteThread(tt); 
     rt = new ReadThread(tt);
 
      tt.pack();
      tt.setLocation(200,70);
      tt.setDefaultCloseOperation(EXIT_ON_CLOSE);
      tt.setVisible(true);
     }
}/**************
  The ReadThread Test Example
**************/     
import java.io.*;public class ReadThread extends Thread
{
    private ThreadTest fileOperation;
    
    public ReadThread(ThreadTest fp)
    {
        fileOperation = fp;       
    }
   
    public void run() {
        while ( (fileOperation.readOperation())!=(-1) ) 
        {                       
            try {
                   sleep((int)(Math.random() * 100));
                }catch (InterruptedException e) { }
        }        
    }
}/**************
  The WriteThread Test Example
**************/     
import java.io.*;public class WriteThread extends Thread
{
    private ThreadTest fileOperation;
    private BufferedReader rf = null;
    char ss[] = new char[1];
    
    public WriteThread(ThreadTest fp)
    {
        fileOperation = fp;        
        try {
         rf =  new BufferedReader(new FileReader("outputtext.txt"));
            }catch(Exception e){}
    }
    
    public void run() 
    {         
           try{
                 while( (rf.read(ss))!=(-1) )
                   {
                   fileOperation.writeOperation((new String(ss)),1);
                      try {
                              sleep((int)(Math.random() * 100));
                           }catch (InterruptedException e) { }
                    }
                  fileOperation.writeOperation((new String(ss)),0);  
               }catch(Exception e){}     
    }
}

Answer 5

多谢wxyxl的GPL精神，这么一大段，我拉下来看看高手的作品先。
回家先，各位不用送了。:)